Maeda MC815C - Time Lag of Crane Is Significant

T-424
H-17 [Natural descending amount for crane is high]
Content Natural descending amount of winch is significant.
Assumed cause
and action to be
taken
Cause Diagnostic method and action to be taken
1
Winch brake cancelation
valve fault
Cleaning or replacement of the spool of winch brake cancelation
valve
2
Winch motor brake operation
fault
Check for winch motor brake operation faults
3 Winch motor operation fault Replace the winch motor
Content Natural descending rate of boom telescoping cylinder is significant.
Assumed cause
and action to be
taken
Cause Diagnostic method and action to be taken
1
Boom telescoping cylinder
fault
★ Stop engine to perform preparations and conduct diagnosis
at a high engine idling speed.
Boom telescoping cylinder at retracting relieving
Cylinder leakage rate: 10 cc / 10 min
2
Counter balance valve
leakage
Check for leakage from the counter balance valve seat parts
3
Sequence valve / mechanical
check valve leakage
Check for leakage from sequence valve / mechanical check
valve
Content Natural descending rate of boom derricking cylinder is significant.
Assumed cause
and action to be
taken
Cause Diagnostic method and action to be taken
1 Boom derricking cylinder fault
★ Stop engine to perform preparations and conduct diagnosis
at a high engine idling speed.
Boom derricking cylinder at retracting relieving
Cylinder leakage rate: 5 cc / 10 min
2
Counter balance valve
leakage
Check for leakage from the counter balance valve seat parts
H-18 [Time lag of crane is significant]
Content Time lag of crane is significant
Assumed cause
and action to be
taken
Cause Diagnostic method and action to be taken
1
Crane control valve operation
valve (spool) operation fault
• Check for malfunction in crane control valve operation valve
spool